1. Field of Invention
The invention is directed to a coupling device for introducing acoustic waves into the body of a life form.
2. Description of the Prior Art
Acoustic waves are introduced into the body of life forms both for diagnostic as well as for therapeutic purposes, such as in apparatuses for ultrasound diagnostics and extracorporeal shock wave lithotripsy (ESWL). The acoustic waves can thereby not be directly introduced into the body of the life form, i.e. on the basis of direct application of the emission surface of the ultrasound transducer or, of the shock wave source against the body surface of the life form. On the contrary, a usually fluid propagation medium for the acoustic waves is generally arranged between the source of the acoustic waves.
For example, it can thus be provided that the source of acoustic waves is introduced into the wall of a bath containing the propagation medium wherein the patient is seated such that the patient assumes the respectively required position relative to the source of the acoustic wave. Apart from the fact that it involves substantial technological outlay, this solution is hygienically problematical. A switch has therefore been made to integrating the source of acoustic waves into a housing filled with the propagation medium, this housing comprising an exit window through which the generated acoustic waves can emerge. The housing containing the source can then be applied against the body surface with its exit window in such a spatial orientation that the diagnostically or, respectively, therapeutically relevant region of the body is charged with the acoustic waves. This solution, which is referred to as "dry coupling", unites the advantage of low technological outlay with that of beneficial hygienic conditions. The exit window, moreover, can be fashioned as a flexible application pillow, with the advantage that a contact area between the exit window and the body surface that is adequately large for the introduction of acoustic waves also derives in body regions wherein parts of the skeleton are located immediately below the body surface.
The problem arises in certain cases that the source of acoustic waves, retaining the "dry coupling" with the body surface, must be particularly automatically adjusted relative to the body with a mechanical adjustment means. For example, this is the case when the focus of the shock waves along the zone to be treated must be adjusted in the treatment of bone conditions in the region of the extremities with focused shock waves, this, for example, potentially making it necessary that the shock wave source be conducted around the extremity in a swivel motion. In these cases, a technologically complicated and expensive adjustment mechanism must be provided for the source of acoustic waves even when the exit window is executed as a flexible application pillow, since it can otherwise not be assured that the contact area between exit window and body surface is adequately large in order to guarantee a good acoustic coupling.
German OS 35 03 702 discloses a "dry" coupling device having an exit window formed by a flexible, stretchable hose section arranged concentrically in the outside part which, together with the outside part, limits an annular space filled with a propagation medium. In this known device, however, the outside part does not constitute an entry wall for the acoustic waves. Instead, the outside part is provided with an opening into which a shockwave source is introduced.